Design and Simulation of a Digital Twin Mobility Concept: An Electric Aviation System Dynamics Case Study with Capacity Constraints

Vertical mobility, as a commercial service, has been strongly focused on the scheduled volume and long-distance mobility services. Thus, limiting its potential coverage, flexibility, and adaptability with high investments and centralized mobility hubs, called airports. In this context, a customized and on-demand air mobility concept providing high flexibility in location combinations and time schedules appears as an unexplored challenge for regional mobility needs. As a result, the aim of this research is to provide a generic framework for various mobility means as well as to design a holistic air mobility management concept for electric vertical mobility for profitable and sustainable operations by providing a service to society. A system dynamics simulation case study applies the conceptual model for an on-demand air mobility network of electric aircrafts in a regional area considering capacity constraints in vertiports, aircrafts, charging, and parking stations. Thus, bottlenecks and delays can be quantified by using a digital twin tool for customized scenarios. Simulation results show how an optimal maintenance management and redistribution of aircraft units improve service indicators in passenger quantity and customer order lead time as well as reduce aircraft on ground time. As a result, a digital twin air mobility network model with simulation capabilities is a key factor for successful operations.

The paradoxes of just-in-time system: an abductive analysis of a public food manufacturing and exporting company in Thailand

Purpose study aims to investigate the implementation and impact of a just-in-time (JIT) system in a food manufacturing and exporting company in Thailand. Design/methodology/approach At the company, the authors used an anomaly case study. The authors performed content analysis on the data collected through semi-structured interviews and direct observations to determine operational flows through customer order, production and delivery. The authors constructed a framework that helped in mapping current operations and subsequently assessing JIT’s impacts; the authors reported the best practices to the company’s owner. Based on the follow-up after a year, the authors used an abductive approach to refine the JIT theory using data from case organizations and relevant studies. Findings The company encountered errors and delays in international delivery owing to inadequate inputs resulting from uncertain agricultural production, delayed contact with freight forwarders, improper documentation and insufficient staffing. Besides the highly centralized system, the limitations of the JIT philosophy contributed to the issues, thereby increasing mental and physical health problems and turnover rate. Owing to these paradoxical effects, the authors extended the JIT theory. Of the study’s several recommendations, the company observed only the following: contacting the freight forwarder after the purchase order confirmation, not production completion. The authors observed increased customer satisfaction, despite the additional cost of booking containers early. Originality/value This research presents a balanced JIT that can minimize JIT’s impacts and resource shortage, owing to demand-supply uncertainties and sustain competitiveness.

Minimizing total tardiness for the order scheduling problem with sequence-dependent setup times using hybrid matheuristics

This paper aims at presenting a customer order scheduling environment in which the setup times are explicit and depend on the production sequence. The considered objective function is the total tardiness minimization. Since the variant under study is NP-hard, we propose a mixed-integer linear programming (MILP) model, an adaptation of the Order-Scheduling Modified Due-Date heuristic (OMDD) (referred to as Order-Scheduling Modified Due-Date Setup (OMMD-S)), an adaptation of the Framinan and Perez-Gonzalez heuristic (FP) (hereinafter referred to as Framinan and Perez-Gonzalez Setup (FP-S)), a matheuristic with Same Permutation in All Machines (SPAM), and the hybrid matheuristic SPAM-SJPO based on Job-Position Oscillation (JPO). The algorithms under comparison have been compared on an extensive benchmark of randomly generated test instances, considering two performance measures: Relative Deviation Index (RDI) and Success Rate (SR). For the small-size evaluated instances, the SPAM is the most efficient algorithm, presenting the better values of RDI and SR. For the large-size evaluated instances, the hybrid matheuristic SPAM-JPO and MILP model are the most efficient methods.

Strategies for achieving customer order flexibility – supplier perspective

PurposeThe purpose of this study is to develop a framework of strategies to achieving customer order flexibility in and related to the order-to-delivery (OTD) process. The purpose is also to investigate how companies prioritize various strategies to achieve customer order flexibility.Design/methodology/approachBased on a literature review, pre-tests and conceptual reasoning, a conceptual framework of strategies related to the order-to-delivery process was developed. The strategies were linked to the order quantity and delivery lead-time flexibility dimensions. This structure resulted in six groups covering enabling as well as remedial strategies. An empirical interview study of ten customer–supplier relationships was conducted.FindingsThe interviews identified additional strategies, thereby expanding the framework. The enabling strategies with the highest median values were “have continuous contact with the customer's purchaser” and “use safety stock of raw materials/semi-finished products”. The remedial strategy with the highest median was “re-plan/re-prioritize the order backlog”. In the delivery sub-process, it was more common to apply remedial strategies for delivery lead-time than for order quantities.Research limitations/implicationsThe developed framework is a contribution to the literature on operational flexibility in and related to the OTD process. It complements existing knowledge by taking a supplier perspective.Practical implicationsSuppliers can use the framework as a tool to understand and systematically achieve better customer order flexibility in and related to the OTD process. Customers can use the framework as a checklist for supplier evaluation and supplier development.Originality/valueFew identified studies include empirical data on customer order flexibility.

Sistem Informasi Wedding Organizer Berbasis Android

Dalam mempromosikan jasa pernikahan, suatu wedding organizer (WO) belum dapat menyajikan informasi paket pernikahan secara lengkap. Banyak permasalahan yang terjadi seperti dalam pengolahan daftar paket pernikahan yang terbaru serta data transaksi yang dikerjakan secara manual yang memungkinan terjadinya kekeliruan informasi dalam detail pemesanan serta pencarian data pesanan pelanggan. Ini juga mengakibatkan kesalahan dalam pencatatan serta perhitungan untuk mengetahui keuntungan dan kerugian usaha. Penelitian ini bertujuan untuk menyajikan data informasi secara lengkap sehingga membantu penyedia jasa mempromosikan layanan secara efektif. Adapun metode yang digunakan adalah metode pengembangan sistem dengan model prototype dimana tahapannya, yaitu: communication, quick plan and modelling quick design, contruction of prototype dan deployment delivery and feedback. Hasil dari penelitian ini menunjukkan bahwa sistem aplikasi WO dapat menginformasikan paket pernikahan secara lengkap, dapat melakukan update terbaru daftar paket pernikahan, proses transaksi pemesan dilakukan secara real time serta informasi data pesanan yang masuk secara otomatis. In promoting wedding services, a wedding organizer is yet able to present complete wedding package information. Many problems occur, such as in the processing of the latest wedding package lists and transaction data that is done manually, which allows for information errors in order details and search for customer order data. This also results in errors in recording and calculating in finding out the profits and losses of the business. This study aimed to present complete information data so as to help service providers promoting the services effectively. The method employed was a system development method with a prototype model where the stages are communication, quick plan and modeling quick design, construction of prototype and deployment delivery, and feedback. The results indicate that the Wedding Organizer Information System can provide complete information on wedding packages, can update the latest list of wedding packages, process customer transactions and information on incoming order data in real time and automatically.